Nerium oleander

Nerium oleander.

Family Apocynaceae > Subfamily Apocynoideae > Tribe Nerieae.
Commonly known just as Oleander it is naturalised, and a weed, in Queensland.
A dense, evergreen shrub up to 6 m high with many stems that bend outwards slightly.
Tissues have a sticky, white latex that is poisonous.

Leaves, in whorls of 3 or sometimes opposite, are on petioles up to 1 cm long.
The narrow, elliptic or lanceolate blades are up to 21 cm long by 3 cm wide.
They are thick and tough, dark green above and paler underneath.
Commonly smooth they may have scattered hairs.

Terminal inflorescences, up to 10 cm long, are clusters of flowers.
The 4 – 5 cm long flowers, on short stalks, are 3 to 4 cm across.
The pink or red flowers can appear most of the year.
Flower parts are in 5’s and the petal lobes are twisted and overlapping in the bud.

The sepals, up to 1 cm long, have glandular hairs at the base.
The bases of the 5 petals are fused into a tube up to 2 cm long.
The lower part is narrow and the upper part flares slightly.
The spreading lobes are up to 3 cm long.
There are hairs inside the tube and on the lobe edges.
At the base of each lobe is a corona with up to 8 small lobes.

The stamens are inserted near the middle of the corolla tube.
The anthers converge to form a cone around the enlarged style head.
There are hairs on the outer surface of the anthers.
The anthers have long, hairy apical appendages and the tails are curved.
The anthers are adherent, but not fused, to the style head.
The large, almost round style head has a projecting rim at the base.
The superior ovary has 2 fused carpels with 2 locules.
There are no nectaries.

The fruit are a pair of tough follicles that split down one side.
Each can be up to around 20 cm long by 1 cm wide.
They have numerous flattened seeds with silky hairs at one end.

There are over 400 named cultivars in standard or dwarf plants.
The single or double flowers can be a solid colour, multicoloured or striped.
The petal edges may be wavy or ruffled.
Colours include white, cream, pink, red, salmon, peach, apricot, yellow and purplish.
A variegated form has leaves with white and yellow.